891
FXUS65 KBYZ 220647
AFDBYZ
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BILLINGS MT
1247 AM MDT FRI MAY 22 2026
KEY MESSAGES
- WARMING TREND AND MOSTLY DRY TODAY THROUGH MEMORIAL DAY; EXPECT
MOUNTAIN SNOW MELT TO INCREASE RIVER FLOWS.
- INCREASING POTENTIAL FOR SHOWERS AND THUNDERSTORMS BY MIDDLE OF
NEXT WEEK; DETAILS HIGHLY UNCERTAIN AT THIS TIME.
DISCUSSION
THROUGH NEXT THURSDAY...
LINGERING SHOWERS OVER THE FAR EAST SHOULD EXIT MT THIS MORNING.
BUILDING HEIGHTS AND SOME DOWNSLOPE WARMING WILL PUSH TEMPS TO THE
60S TODAY. SATURDAY WILL BE WARMER YET WITH HIGHS MOSTLY IN THE
70S. THOUGH THE NEXT TWO DAYS WILL BE MOSTLY DRY, SATELLITE
IMAGERY SHOWS A COUPLE OF WEAK UPSTREAM SHORTWAVES IN THE NW FLOW
ALOFT THAT MAY RESULT IN SLIGHTLY MORE ACTIVE WEATHER THAN
PREVIOUSLY THOUGHT. ONE SHORTWAVE IS DROPPING THRU BC AND THE NEXT
IS RIGHT ON ITS HEELS NEAR SOUTHEAST AK. HIGH RES MODELS ARE
STARTING TO PAINT WEAK CONVECTION OVER OUR W/NW THIS AFTERNOON &
EVENING...A RESULT OF MID LEVEL MOISTENING AND SHALLOW CAPES OF
100-200 J/KG DURING THE PEAK HEATING HOURS. A MENTION OF ISOLATED
SHOWERS IS WARRANTED. SATURDAY IS MORE UNCERTAIN BUT THE SECONDARY
WAVE MAY DO SOMETHING SIMILAR EXCEPT OVER THE EAST PER TIMING OF
THE PV MAX, BUT IS ALSO POSSIBLE THE AIR MASS IS TOO DRY BY THEN.
MODEL DIFFERENCES EXIST HERE.
FLOW ALOFT BACKS TO WESTERLY SUNDAY THEN SOUTHWESTERLY MONDAY IN
ADVANCE OF THE NEXT PACIFIC TROF. THE WARMER FLOW WILL RESULT IN
TEMPS IN THE 80S, AND PERHAPS 90F MONDAY AS 700MB TEMPS WARM TO
+10C TO +12C. THESE DAYS WILL BE MOSTLY DRY BUT AGAIN, WEAK
DIURNAL CONVECTION IS A POSSIBILITY ESPECIALLY CLOSE TO THE
MOUNTAINS & FOOTHILLS (PERHAPS SNOWMELT WILL HELP TO ELEVATE
BOUNDARY LAYER MOISTURE?). SOMETHING TO KEEP IN MIND IS THAT THE
WARMER TEMPS AND MOUNTAIN SNOW MELT WILL RESULT IN INCREASED FLOWS
ON AREA RIVERS AND STREAMS. HEADS UP TO THOSE THAT WILL BE OUT
AND ABOUT OVER THE MEMORIAL DAY WEEKEND.
THINGS MAY GET MORE INTERESTING BY THE MIDDLE OF THE WEEK AS THE
PACIFIC TROF MOVES INLAND IN SOME FASHION. CLUSTER ANALYSES REMAIN
HIGHLY SPREAD IN POTENTIAL SOLUTIONS, BUT IT SHOULD BE NOTED THAT
A SLOWLY EVOLVING CUT OFF LOW OVER THE INTERMOUNTAIN WEST HAS THE
HIGHEST PROBABILITY PER TODAY'S 12Z ENSEMBLES. THERE ARE THREE
POSSIBILITIES: (1) A FASTER OPEN WAVE THAT BRINGS A BRIEF CHANCE
OF PRECIP AND PERHAPS SOME WIND; (2) A CLOSED LOW THAT SETS UP TOO
FAR TO OUR SW/S TO BRING US MEANINGFUL PRECIPITATION, BUT IS A
WETTER SCENARIO THAN #1; AND (3) A CLOSED LOW THAT TRACKS SLOWLY
THROUGH THE GREAT BASIN INTO WY, A FAVORABLE POSITION FOR
SIGNIFICANT RAINFALL. IF #3 VERIFIES WE COULD BE LOOKING AT RAIN
ON SNOW IN THE HIGH COUNTRY. OBVIOUSLY UNCERTAINTY IS VERY HIGH SO
STAY TUNED. ONE THING THAT IS A BIT MORE CERTAIN: AS THE LOW
APPROACHES WE WILL SEE AT LEAST A MODEST INCREASE IN PLAINS
MOISTURE, SETTING UP INCREASED POTENTIAL FOR THUNDERSTORMS TUESDAY
& WEDNESDAY, WHICH MAY INCLUDE A RISK OF SEVERE STORMS. AS FOR
TEMPERATURES, ENSEMBLE CONSENSUS IS FOR GRADUAL COOLING BUT STILL
WARM TUESDAY & WEDNESDAY, FOLLOWED BY A COOLER AND POTENTIALLY
WETTER THURSDAY. ALL OF THIS IS SUBJECT TO CHANGE.
JKL
AVIATION
06Z DISCUSSION...
UPPER TROF OVER EASTERN QUARTER OF THE FORECAST AREA LATE EVENING
WILL TRACK EAST OF THE AREA BY SUNRISE, PULLING PRECIPITATION AND
MOST OF THE REDUCED FLIGHT CONDITIONS (KBHK) WITH IT. THERE MAY BE
POCKETS OF FOG (MVFR/LOCAL IFR) FOR AREAS FROM ROSEBUD COUNTY
EASTWARD WHERE SIGNIFICANT PRECIPITATION HAS FALLEN IN THE PAST 12
HOURS AND CURRENT DEW POINT DEPRESSIONS ARE UNDER 5 DEGREES,
INCLUDING KMLS, K4BQ, AND KBHK. ANY FOG SHOULD DISSIPATE BY 15-16Z
WITH DRIER NORTHWEST WINDS BUILDING OVER THE AREA FOR TOMORROW
AFTERNOON. THERE WILL STILL BE ENOUGH INSTABILITY AND RESIDUAL
MOISTURE AROUND FOR ISOLATED SHOWERS (SCATTERED FOR THE WESTERN
MOUNTAINS) FOR THE AFTERNOON HOURS, DIMINISHING QUICKLY AFTER 00Z.
WIND SPEEDS OVER THE NEXT 24 HOURS WILL BE GENERALLY UNDER 15KTS.
CHAMBERS
PRELIMINARY POINT TEMP/POPS
TDY SAT SUN MON TUE WED THU
-------------------------------------------------------
BIL 068 044/077 051/086 054/090 057/088 054/076 051/075
0/U 20/U 00/U 00/U 12/T 55/T 42/T
LVM 066 038/074 045/082 049/085 050/079 045/070 043/070
2/W 20/B 00/U 02/T 14/T 55/T 33/T
HDN 068 038/077 045/088 050/090 053/090 053/077 049/077
0/U 00/U 00/U 00/U 01/B 44/T 33/T
MLS 069 041/077 045/086 051/091 059/092 058/080 053/080
0/U 01/U 00/U 00/U 01/N 33/W 32/T
4BQ 065 039/075 046/085 050/090 060/090 057/078 052/077
0/B 01/U 00/U 00/U 01/U 34/T 43/T
BHK 065 037/074 044/087 050/090 058/090 058/080 052/078
1/B 01/U 00/U 00/U 00/N 24/T 43/T
SHR 064 034/074 040/081 044/086 047/087 047/074 044/073
0/U 01/U 00/U 01/U 02/T 46/T 44/T
BYZ WATCHES/WARNINGS/ADVISORIES
MT...NONE.
WY...NONE.
WEATHER.GOV/BILLINGS
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